Telephone system



C. B. FOWLER.

TELEPHONE SYSTEM.

APPLICATION FILED DEC. 16, 1919.

Patented Aug. 9, 1921.

hvenfor: C/a/"e/vce 15, Pow/er UNITED STATES PATENT OFFICE.

CLARENCE B. FOWLER, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRICCOM- PANY, INCOBPORATED, OE NEW YORK,

N. Y., A CORPORATION on NEW YORK.

' TELEPHONE SYSTEM.

Specification of Letters Patent. Patented Aug, 9, 1921.

Application Tiled December 16, 1919. Serial No. 345,311. 5

To all whom it may concern Be it known that I, CLARENCE B. FOWLER, acitizen of the United States, residing at New York, in the county of NewYork, State of New York, have invented certain new and usefulImprovements in Telephone Systems, of which the following is a i'ull,clear, concise, andexact description. p

This invention relates to telephone systems and has for its object theproduction of improved signaling means for such systems. V

In the present embodiment of this invention means, individual to asubscribers line, are provided at a central office whereby afterrestoring his receiver to the switchhook a calling subscriber may, byremoving his receiver from the. switchhook before the disconnection ofthe cord circuit from his line, operate a distinctive signal to recallthe operator. The operator on noticing the recall signal mayidiscontinue its operation by touching the sleeve contact of theanswering plug or ack with the tip of the plug of any cord circuit, asin making a busy test,

and may then dep'ress her listening keyto connect her head-setwith theline.

Byprovidingapparatus individual to the subscribers lines for furnishinga distinctive recall signal, it is unnecessary to install special cordcircuits when thisfeature is desired by lines terminating in an exchangeprovided with cord circuits not arranged for such recall signals. I Y

Figure 1 of the accompanying drawing is a diagrammatic representation ofthatpon tion of a telephone system 'necessaryto an understanding oftheinvention. There is shown a subscribers line 1, which terminates at acentral oflice in an'answering jack 2, and in multiple jacks 3, of whichbut one is shown. An answering plug 4c of one cord circuit is shown, butany number of cord circuits may be used. The relays and line.

lamp shown are individual to the line, and the supervisory lamp to thecord circuit,but the battery and interrupter may be common to severalcords and lines. Fig. 2 of the drawing shows diagrammatically the methodof discontinuing the recall signal by touching with the tip of an idleplug, the sleeve contact of the plug of a connected cord circuit. It isbelieved that the invention will be readily understood from aconsideration ofthe operation of the system, which is asfollows:

A subscriberdesiring toinitiate a call removes his receiver from itshook, thereby completing an energizing circuit for line relay 5 whichmay be traced from grounded battery through the right hand winding ofrelay 5 ,-back contact and inner armature of cut-01f relay 6, and thencethrough the subscribers line loop, outer armature and back contact ofrelay 6, through'the left hand winding of relay 5 to ground. Relay 5 inenergizing completes a circuit from grounded battery through lamp 7contact and innermost armature of relayb, back contact and innerarmature ofsleeve relay '8, to ground. Line lamp 7 is lighted ingrounded battery through lamp 9, sleeve contacts of plug 4., and jackQ,through the right hand low resistance winding of sleeve relay 8 and theleft hand high resistance winding of this relay to. ground. Relay 8 isenergized in this circuit, butis of such high resistance that lamp 9does not light.

In attracting its inner armature relayy8.

interrupts, the circuit of line lamp 7, to extinguish this lamp. Inattracting its outer armature relay 8; connects battery throughresistance 11, to the sleeve contacts of the 4 in jack 2, a circuit iscompleted from multiple jacks of the calling line in order to furnish abusy test.

At the completion of the conversation when the calling subscriberreplaces his re-- ceiver on its switchhook he interrupts the previouslytraced circuit for line relay 5 and this relay becomes inert. A circuitis thereupon completed from grounded battery through the winding ofrelay 12, back contact and outermost armature of relay 5,

front contact and inner armature of relay 8 to ground. Relay 12 inattracting'its left hand armature completes a locking circuit.

for itself independent of the contact of relay 5, and in attracting itsright hand armature completes a circuit from ground,

back contact and middle armature of relay 5, right hand armature andfront contact of relay 12, through the right hand winding of relay 8,sleeve contacts of jack 2 and plug 4, through supervisory lamp 9 togrounded battery. The high resistance winding of relay 8 is shunted bythis circuit to light supervisory lamp 9 to furnish a disconnect signal,but relay 8 is held energized.

Should thesubscriber desireto recall the operator,aft er having replacedhis receiver on its swit'chhook, he removes it therefrom and againcompletes the circuit for the line relay; Relay 5 in attracting itsmiddle armature includes interrupter 13 in thepre .viously tracedcircuit for the supervisory grounded, serially connected windings'ofrelay 8, thus shunting these windings; Relay 8 in deenergizing opens thelocking circuit for relay 12, which deenergizes to open the circuit forthe supervisory lamp 9, thus extinguishing this lamp. Upon removing theplug with which she has touched the sleeve of plug 4: the operatorbreaks the shunt circuit for relay 8 and this relay is again energizedthrough both windings in series with the line lamp and the'relays are"in the condition in which they normally should be during the progress ofa call.

When line 1 is called, battery is connected through the sleeve of thecalling plug (not shown) and the sleeve of multiple jack 3, through theouter armature and back contact of relay 8 and the winding of cut-01frelay 6 to ground. Relay 6 is eninserted into ergized in this circuit tocut ofi' line relay 5 which supplies talking current to line 1 when itis a calling line, talking current now being supplied through thecalling end of the connected cord circuit.

What is claimed is:

1. In a telephone system the combination with a telephone line, a cordcircuit for extending said line, a signaling device individual to saidcord circuit, and means individual to said telephone line responsive toan interruption of said linefor operating said signaling device in onemanner to give a disconnect signal, said-means being responsive to asubsequent'closure of said line to operate said signaling device in adifferentman'ner to give a recall signal.

2. In a telephone system the combination with a telephone line, a "cordcircuit for extending said line, a signaling device associated with saidcordcirc'uit, a set of relays individual to said line operated inresponse to the closure of said line'a-iid the connection of said cordcir'cuitto said line to prepare an operating circuit for said signalingdevice, a relay operated in response to the interruption of said linefor completing said operating circuit, and'an interrupter included insaid operating circuit, in responseto a subsequent closure of said lineto operate said signaling device inter-J mittently.

3. In a telephone system the combination with a telephone lineterminating in aspring jack, a number of'cord circuits for. associationtherewith, signaling devices associated therewith, a line relayresponsive to the closure of said telephone line, a second relayindividual to said; line operated. in response to the" deenergization ofsaid line relay to complete an operating circuit for one ofsaid'si'gnal-ihg devices, and means for causing the release of saidsecond relay by making electrical connection between a'contact of anidle plug, and a contact of'a plug the spring jack of said line circuit;p i

In witness whereof, I hereunto subscribe my name this Gth'day ofDecember, A. D.

CLARENCE B} FOWLER;

